Path extraction of low SNR dim targets from grayscale 2-D image sequences

Ergüven, Sait
In this thesis, an algorithm for visual detecting and tracking of very low SNR targets, i.e. dim targets, is developed. Image processing of single frame in time cannot be used for this aim due to the closeness of intensity spectrums of the background and target. Therefore; change detection of super pixels, a group of pixels that has sufficient statistics for likelihood ratio testing, is proposed. Super pixels that are determined as transition points are signed on a binary difference matrix and grouped by 4-Connected Labeling method. Each label is processed to find its vector movement in the next frame by Label Destruction and Centroids Mapping techniques. Candidate centroids are put into Distribution Density Function Maximization and Maximum Histogram Size Filtering methods to find the target related motion vectors. Noise related mappings are eliminated by Range and Maneuver Filtering. Geometrical centroids obtained on each frame are used as the observed target path which is put into Optimum Decoding Based Smoothing Algorithm to smooth and estimate the real target path. Optimum Decoding Based Smoothing Algorithm is based on quantization of possible states, i.e. observed target path centroids, and Viterbi Algorithm. According to the system and observation models, metric values of all possible target paths are computed using observation and transition probabilities. The path which results in maximum metric value at the last frame is decided as the estimated target path.


Direction of arrival estimation by array interpolation in randomly distributed sensor arrays
Akyıldız, Işın; Tuncer, Temel Engin; Department of Electrical and Electronics Engineering (2006)
In this thesis, DOA estimation using array interpolation in randomly distributed sensor arrays is considered. Array interpolation is a technique in which a virtual array is obtained from the real array and the outputs of the virtual array, computed from the real array using a linear transformation, is used for direction of arrival estimation. The idea of array interpolation techniques is to make simplified and computationally less demanding high resolution direction finding methods applicable to the general...
Application of ODSA to population calculation
Ulukaya, Mustafa; Demirbaş, Kerim; Department of Electrical and Electronics Engineering (2006)
In this thesis, Optimum Decoding-based Smoothing Algorithm (ODSA) is applied to well-known Discrete Lotka-Volterra Model. The performance of the algorithm is investigated for various parameters by simulations. Moreover, ODSA is compared with the SIR Particle Filter Algorithm. The advantages and disadvantages of the both algorithms are presented.
Radar range-doppler imaging using joint time-frequency techniques
Akhanlı, Deniz; Dural Ünver, Mevlüde Gülbin; Department of Electrical and Electronics Engineering (2007)
Inverse Synthetic Aperture Radar coherently processes the return signal from the target in order to construct the image of the target. The conventional methodology used for obtaining the image is the Fourier transform which is not capable of suppressing the Doppler change in the return signal. As a result, Range-Doppler image is degraded. A proper time-frequency transform suppresses the degradation due to time varying Doppler shift. In this thesis, high resolution joint-time frequency transformations that c...
An investigation of jamming techniques through a radar receiver simulation
Kırkpantur-Çadallı, Atiye Aslı; Koç, Seyit Sencer; Department of Electrical and Electronics Engineering (2007)
In this study, various jamming techniques and their effects on detection and tracking performance have been investigated through a radar receiver simulation that models a search radar for target acquisition and single-target tracking radar during track operation. The radar is modeled as looking at airborne targets, and hence clutter is not considered. Customized algorithms have been developed for the detection of target azimuth angle, range and Doppler velocity within the modeled geometry and chosen radar p...
Implementation of a digital signal synthesizer with high spurious free dynamic range
Kılıç, Argun; Yılmaz, Ali Özgür; Department of Electrical and Electronics Engineering (2006)
Today’s analog modulators and upconverters are inadequate to synthesize and modulate signals with high ‘Spurious Free Dynamic Range’ (SFDR). Thus, the main objective of this thesis is to design and implement a ‘Digital Signal Synthesizer’ (DSS) that is capable of synthesizing signals between 50-100 MHz with 60dB SFDR and to modulate them variable symbol rates and modulation techniques with very high phase/frequency resolution and switching speed while keeping the amplitude modulation occurring during a modu...
Citation Formats
S. Ergüven, “Path extraction of low SNR dim targets from grayscale 2-D image sequences,” M.S. - Master of Science, Middle East Technical University, 2006.